Quantitative Risk Assessment (QRA) provides quantitative analysis of risks for an operation and its parameters. Qualitative risk analysis determined the probability of a risk event occurring, and its impact if it occurs. QRA assigns numerical value or quantitative rating to the risk, and analyses the probability of the risk and estimates its impacts. QRA is deployed widely in the chemical process and petrochemical industry. 

QRA should be carried out during the establishment of the plant and whenever changes are made to its operations such as plant expansion, addition of new machines or substance and procedures.